Clamping element for storage battery plate stacks

ABSTRACT

A plate stack clamping element is formed of adjacent leaf springs preformed to diverge where they extend beyond the plate stack. Compression of the diverging portions creates large area contact clamping force against the plate stack.

This is a division of application Ser. No. 042,577, filed May 25, 1979,now U.S. Pat. No. 4,342,449.

The invention relates to a clamping element for holding plate stacks oflead storage batteries and which defines a cell separating partitionwithin a cassette conforming to the plan cross section of a blockcasing.

In the manufacture of batteries, it is customary to assemble six platestacks, each of which consists when finished of positive and negativeelectrodes with intervening separators, united into a plate assemblywhile leaving narrow interstices free. This assembly is then furtherprocessed. For example, pole bridges must be cast or welded onto theplate vanes of the electrodes and these in turn must be provided withcell connectors. This presupposes that all the plate stacks are alreadypositioned relative to each other in the same manner in which they aredestined to be during subsequent final introduction into the blockcasing. The spaces between plate stacks must be so dimensioned that theyare subsequently precisely filled by the cell separating partitions ofthe block casing.

There is already known apparatus for receiving and prepositioning of theplate stacks which makes possible unimpeded and careful processing ofthe stacks by insertion in an appropriate retainer. For example, inGerman Offenlegunsschrift (Patent Publication) No. 2,554,069 and U.S.Pat. No. 4,065,116 there is described an arrangement of pneumaticclamping elements which project from the sides into the intersticesbetween the plate stacks and which are inflated by supplied compressedair in such manner that the plate stacks are firmly clamped relative toeach other by the resultant compression forces.

By virtue of new injection molding techniques and appropriate syntheticplastic selection, the cell separating partitions of block casings cancurrently be kept so extremely thin that essentially the entire interiorremains almost completely available for the reception of plate stacks.

A drawback of the known clamping element is that the possibility whichis created by the thin separating partitions will not be fully exploitedbecause each clamping element individually requires a predeterminedminimum thickness for structural reasons. For pneumatic clampingelements, this is determined by the presence of inflatable membranepockets in an open frame of the elemental plates, and by the additionaljuxtaposition of the actual clamping sheets to the elemental plate. Thisimparts to the clamping element even in its unclamped state a thicknessof almost four millimeters.

Less serious drawbacks of the pneumatic clamping element reside in thedanger that these can become soiled and that leaks in the pressurepiping system can occur.

Accordingly, it is the primary object of the invention to provide aclamping element for holding plate stacks for further processing whichmakes it possible to clamp the plate stacks even with minimalinterstices and which provides reliable pressure against the sides ofthe plate stacks even for wide thickness tolerances.

This and other objects which will appear are achieved in accordance withthe invention by making the clamping elements of two closely adjacent,pre-formed leaf springs.

For further details, reference is made to the discussion which followsin light of the accompanying drawings wherein

FIGS. 1 and 2 are diagrammatic illustrations of an embodiment of theinvention in two different stages of its utilization;

FIGS. 3 and 4 are likewise diagrammatic illustrations also showing anactuating mechanism for the embodiment of FIGS. 1 and 2; and

FIG. 5 is a three-dimensional representation of a portion of such anembodiment.

Referring to FIG. 1, the elements embodying the present invention arepositioned within an extendable telescoping cassette. Their utilization,however, is also possible in cassettes with fixed outward configuration.

The clamping elements 1 embodying the invention which are shown in FIG.1 in the unclamped state consist of two thin simple leaf springs 2 whichhave been given an angular bend through performing. The leaf springs 2are close to but not firmly up against the sides of plate stacks 3.

The telescoping cassette has extension elements 4 which enable atelescoping of the clamping elements from left to right by apredetermined amount of play beyond the subdivision distance of thecells. However, they have no sigficance for the subject matter of thisinvention.

FIG. 2 shows the principle of clamping of the leaf springs 2. This takesplace by squeezing together of the two spring arms 5 which project,forklike, from the regions of the cassette corresponding to the cellseparating partitions, i.e. the interstices between the plate stacks 3.In so doing, the leaf springs revolve about their common contact edge atwhich they may be attached for example by means of a clip. Because theleaf springs have been angularly preformed, the compression of springarms 5 automatically creates the clamped condition. This state ismaintained during further processing of the block assembly by a latch 6.By unlatching there is restored the unclamped state of the clampingelements according to FIG. 1. After the cassette is pulled open in thetransverse direction the finished block assembly can be lowered directlyinto the block casing positioned beneath it.

In accordance with the invention the leaf springs 2 have a thickness ofbetween about 0.4 mm and 2 mm, preferably about 1 mm, and are made ofspring steel. Due to the elasticity of the clamping elements there isachieved a large area contact with the plate stack 3. Such clampingelements are rugged and trouble free and inexpensive to make. However,the special advantage of the clamping element according to the inventionis that the leaf springs 2, which are closely adjacent even in theclamped state, require a thickness which is no greater than that of thespring sheet material of which they are made.

FIG. 3 shows the clamping element embodying the invention correspondingto diagrammatic FIG. 1 initially in the unclamped state. For itsactuation there is a slideable wedge-shaped element 7 which ispositioned between the spring arms 5 of any two adjacent clampingelements 1. Good contact and good guidance of the wedge-shaped element 7is assured by providing the ends of the spring leaves with the loops 8and also by connecting the respective spring arms 5 with helical springs9 through the intervening wedge-shaped element 7. The helical springs 9simultaneously impart to the clamping elements the restoring force whichis required for unclamping. The wedge-shaped elements 7 are providedwith a recess for the passage of helical springs 9.

In FIG. 4 the clamping element embodying the invention is shown in theclamped state corresponding to the diagrammatic illustration of FIG. 2.The clamping is produced by sliding of the wedge-shaped elements 7relative to loops 8 which it presses closely against each other duringits movement perpendicularly to the plate block assembly. The leafsprings 2 thereby mold themselves with large area contact and firmlyagainst plate stacks 3. The clamping element is latched in this positionof the wedge-shaped elements 7 as shown in diagrammatic FIG. 2, whereasit is unlatched in the position of the wedges shown in FIG. 3.

The wedge-shaped elements 7 which are attached to a common arm 10, slideduring their two and fro movement immediately above the bottom of thecassette. The movement drive can be provided, for example, as shown inFIG. 5, by means of a cam shaft in conjunction with restoring springs. Agear rack mechanism can also be used.

As is readily visible in FIG. 4, the spacing between adjacent clampingelements is determined by the thickness of wedge-shaped element 7. Inorder to be able to process in the same cassette plate stacks of greaterthickness for other types of batteries, the spacing between the clampingelements must be increased by a corresponding amount. In the clampingelement embodying the invention, this spacing increase becomes possiblebecause the wedge-shaped element is separable along line A--A, andbetween its two halves a suitable spacing member of desired width can beinserted.

For holding and orienting of the clamping elements, guide rods 11 (FIG.5) or rails are provided in the plane indicated by line B--B. Ifdesired, the clamping elements may be displaced along these.

The actuating elements for the clamping of the leaf springs need notnecessarily be positioned within the cassette but may also be placedoutside it. In the latter case, the cassette can be of very simple form.This is advantageous for rapid replacement in a manufacturing plant.

We claim:
 1. A clamping system for holding a plurality of plate stacksof lead storage batteries constituting separating partitions within acassette conforming to the plan dimension of the storage battery's blockcasing, wherein the clamping system includes a plurality of clampingelements each having two closely adjacent preformed leaf springs, andwedge-shaped elements which are slideable between the spring portions ofadjacent clamping elements to provide means for alternative clamping ofthe two leaf springs so that said springs are moved toward each other,and unclamping of the two leaf springs so that said springs are movedapart from each other, so as to permit insertion into the block casingand closing of the assembly.
 2. The system of claim 1 wherein the leafsprings are made of a spring sheet material of a thickness of about 0.4mm to about 2 mm, and preferably about 1 mm.
 3. The system of claim 2wherein the spring sheet material is spring steel.
 4. The system ofclaim 1 wherein the leaf springs have portions which extend outside thecassette and are deflectable toward each other.
 5. The system of claim 1wherein wedge-shaped elements which are slideable between the springportions of adjacent elements are provided for the clamping of thesprings.
 6. A clamping system for holding a plurality of plate stacks oflead storage batteries constituting separating partitions within acassette conforming to the plan dimension of the storage battery's blockcasing, wherein the clamping system includes a plurality of clampingelements each having two closely adjacent preformed leaf springs, eachof the two springs having a first and second portion, wherein said firstportions lie flat against one another when the second portions of thesprings diverge, and wherein said first portions diverge from oneanother when the second portions lie flat against each other, and meansfor alternatively moving said springs apart from and toward each otherso as to permit insertion into the block casing and closing of theassembly.
 7. A clamping system for holding a plurality of plate stacksof lead storage batteries constituting separating partitions within acassette conforming to the plan dimension of the block casing, whereinthe clamping system includes a plurality of clamping elements eachhaving two closely adjacent preformed leaf springs, and wedge-shapedelements which are slideable between the spring portions of adjacentclamping elements, in order to provide alternatively clamping andunclamping of the two leaf springs of each element, said clampingelements being coupled together to move as a group.
 8. In a cassetteconforming to a plan cross section of a block casing of lead storagebatteries having a clamping system for holding a plurality of platestacks of lead storage batteries constituting separating partitions, theimprovement which comprises, said clamping system including a pluralityof clamping elements each having two closely adjacent preformed leafsprings, and wedge-shaped elements which are slideable between thespring portions of adjacent clamping elements in order to providealternatively clamping and unclamping of the two leaf springs of eachelement.
 9. The cassette of claim 8 wherein wedge-shaped elements whichare slideable between the spring portions of adjacent elements areprovided for the clamping of the springs.
 10. In a cassette conformingto a plan cross section of a block casing of lead storage batterieshaving a clamping system for holding a plurality of plate stacks, theimprovement which comprises, said clamping system including a pluralityof clamping elements each having two closely adjacent preformed leafsprings, each of the two springs having one portion which lies flatagainst the adjacent portion of the other spring when the remainingportions of the two springs diverge, and which diverges from theadjacent portion of the other spring when the remaining portions lieflat against each other.
 11. The cassette of claim 10 wherein theclamping elements are coupled together to move as a group.